The lateral nucleus (LA) of the amygdala has been implicated in the acquisition and consolidation of Pavlovian fear condition. During expressing, information is transmitted from LA to the central nucleus (CE) which controls fear related responses. Preliminary data suggests CE may also play a role along with LA, in fear learning and that CE activity is potentiated following thalamic stimulation. This proposal plans to investigate if CE is involved in the acquisition and consolidation of auditory fear conditioning. First, experiments will assess whether CE, as well as LA, is necessary for acquisition. Next, the specific role of CE in fear conditioning will be examined using functional inactivation and manipulations of intracellular cascades implicated in consolidation of long-term memory. Finally, the source of potentiated responses in CE will be examined. If activity and plasticity in CE, along with LA, is necessary for acquisition and/or consolidation of learned fear, manipulations of CE will disrupt potentiations and impair fear behavior. These investigations are aimed to clarify the neural basis of learned fear so that the information can be applied to study and treatment of human psychological disorders in which abnormal functioning of the amygdala has been implicated.